In an increasingly networked world, more and more traffic, such as data, voice, and video, is transmitted over public and proprietary networks. Wireless networks, in particular, are becoming increasingly popular as networks through which subscribers obtain both voice services (e.g., telephone calls) and data services (e.g., email and web surfing).
Wireless networks may support location-based calling, in which a call initiated by a caller may be handled by the network based on the location of the user. For example, “N11” calls include a set of special abbreviated dialing numbers which allow access to special services. In an N11 call, such as a 9-1-1 call, the location of the wireless caller may be routed through the telephony network based on the location of the cell or sector to which the caller is assigned. Location-based calling may also be supported using network “short codes,” in which a wireless caller may dial a special short code (e.g., five or six digits) instead of a normal, longer, telephone number.
In conventional wireless networks, such as a 1xRTT network, location-based calling may be implemented through mobile switching centers (MSCs) in the network. The MSCs may receive information identifying the cell or sector at which a call originated, and may use this information to route the call to an appropriate destination. For example, a 9-1-1 call may be routed to an emergency response center near the caller's location.
Internet Protocol (IP) multimedia subsystem (IMS) is a standard used to deliver IP multimedia to client devices. Under IMS, communication devices, such as mobile telephone devices, may connect to control servers that monitor and control the connectivity of the mobile device to the telecommunication network. IMS may be particularly used to enable multi-media services over IP networks.
In wireless IMS over IP networks, the physical network may include traditional wireless communication stations (macro cell base stations) installed at fixed locations and used to communicate with the wireless mobile terminals. Another type of base station, called a femtocell, may also be used in such networks. A femtocell may be a small wireless base station, typically designed for use in a home or small business. The femtocell may connect to a service provider's network via broadband (such as DSL or cable). A femtocell may allow service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable.
Because IMS over IP networks operate at a network layer above the wireless network, IMS may not track or record the location of a caller. It may, however, be desirable to provide location-based calling for wireless callers using IMS, including wireless callers that connect through femtocells in a IMS wireless network.